The present disclosure relates to vacuum brake systems and more specifically to an interface between an air brake system and a vacuum brake system.
Electronic control systems are used to control brakes on locomotive/s and the attached train using an air brake system. The typical air brake system uses a single pressurized air pipe brake pipe, (ABP) to control the train and control the automatic air brake on the locomotive from pressure changes in air brake pipe ABP. The air brake pipe ABP is controlled directly by the locomotive electronic brake systems system. The CCB system from New York Air Brake Corporation is an example of such a locomotive electronic brake system.
Many trains in some countries use a vacuum brake system, in which a vacuum brake pipe (VBP) is used to control the brakes in the train. The brakes on the train are released by creating a vacuum in the vacuum brake pipe VBP and are applied by venting the vacuum brake pipe VBP to atmosphere. Brake cylinders on the train, directly connected to the VBP, use atmospheric pressure to apply the brakes when the vacuum brake pipe VBP is vented to atmosphere. For an atmospheric pressure of 1013 mbar (30 inches Hg, sea level), the vacuum brake pipe VBP is usually exhausted to a pressure of 640 mbar (19 inches Hg). At higher altitudes greater than 1500 m above MSL, it maybe less. On each train the lead locomotive has a pneumatic vacuum relay valve to control the vacuum brake pipe VBP in response to the air brake pipe ABP. There is no emergency condition with vacuum brakes, but they can achieve rapid response to an emergency condition if the driver's brake valve is used to cause an emergency condition on the air brake pipe ABP.
With the updating of locomotive air brake systems to replace pneumatic locomotive brake controllers with electronic-pneumatic brake controllers, a number of pneumatic devices have been eliminated. In order to achieve the results with vacuum brakes, this requires a new interface between an air brake system and a vacuum brake system.
The present locomotive brake control system includes an air brake pipe, a vacuum brake pipe, a compressed air source, a vacuum source, and air brake cylinders for applying and releasing brakes on the locomotive. When vacuum mode is selected, a vacuum brake pipe transducer senses brake apply and release signals on the vacuum brake pipe and thereby transfer the control of air brakes on the locomotive from responding to air brake pipe ABP (in air brake mode) to responding to the vacuum brake pipe VBP when in vacuum mode.
By using the VBP pipe to control the locomotive brakes when in vacuum mode, the venting of vacuum from the VBP by a break-in-two of the VBP will also automatically apply the brakes on the locomotive. Another reason is that use of the VBP provides braking on the locomotive that is responding to the same brake command as that on the train, i.e. the VBP.
There is no separate vacuum brake controller for the vacuum relay valve; the same control equipment is used in vacuum mode as that used in air brake modes. The only difference is that the locomotive brake cylinder command will be developed in response to the VBP instead of the ABP. Dynamic brake interlocks, bail and Independent control work exactly the same as in air brake modes.
These and other aspects of the present disclosure will become apparent from the following detailed description of the disclosure, when considered in conjunction with accompanying drawings.